Surgical Dermatology Unit

What is Pilonidal Sinus?

A pilonidal sinus (PNS) is a small cyst or abscess that occurs in the cleft at the top of the buttocks. Pilonidal means a 'nest of hairs'.

Fig 14.1: Sinus Tract Formation Clinical Reference

A PNS usually contains hair, dirt, and debris. It can cause severe pain and often become infected, oozing pus and blood with a foul odour.

A sinus tract is a narrow tunnel typically between a focus of infection in deeper tissues to the skin surface, discharging pus from time to time.

What is causes?

Ingrowing hairs are the most common cause. It is common to find hair follicles inside the sinus.

Can appear after an injury to the sacrococcygeal region or irritation from riding in bumpy vehicles.

Common in army jeep drivers due to hours of bouncing on hard seats, causing irritation and pressure around the natal cleft.

Pain and swelling at the bottom of the spine.

Reddening of the skin (Abscess formation).

Drainage of pus or blood from a skin opening.

Foul smell from draining pus.

Raised temperature with any above symptoms.

No symptoms? Keep area clean and shave hairs.

Early intervention can prevent a sinus from developing into a severe abscess requiring surgical incision.

Sitting in a warm bath may decrease pain and progress of the infection.

Consult a doctor if symptoms occur. Antibiotics alone do not improve it.

"A pilonidal cyst is an abscess or boil. It needs to be drained, or lanced, to improve."